This Part Fits the following kits / parts:

#86971 - LOCKING HEX WHEEL HUB 12mm

E-FIRESTORM

Use this complete set of Locking Hex Wheel Hubs to improve and
enhance the the durability of your E-Firestorm or Firestorm 10T!
These metal hex hubs will help extend the life of the wheels and
drivetrain. These hex hubs will also fit other trucks to allow
fitting of HPI truck wheels!

To secure the setscrews in place use #Z159 HPI Threadlocking
Compound.